JPH1020070A - Main steam line plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel main steam line plug which can excellently seal a main steam nozzle without using any counterpressure support, ring. SOLUTION: This main steam line plug is provided with a plug main body which is inserted into the inside of a main steam nozzle 2 of a nuclear reactor pressure vessel so as to seal the main steam nozzle 2, movable pieces 12a, 12b, in each of which a bent part, is journalled on the circumference part of the plug main body while one end is freely protruded/retracted to/from the outside of the plug main body and an Lshaped cross section is provided, and a pressing member which is arranged in a shaft center part of the plug main body freely reciprocatively and presses the movable pieces 12a, 12b so as to protrude them by means of pressure inside the main steam nozzle 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main steam line plug inserted into a main steam nozzle of a reactor pressure vessel filled with pure water from the inside thereof in a watertight manner.

[0002]

2. Description of the Related Art As shown in FIG. 5, a boiling water reactor generally called a BWR has a plurality of main steam nozzles 43 at an upper part of a reactor pressure vessel 42 containing a reactor core 41, and these main steam nozzles 43 are provided. Through a main steam pipe 44 connected to the nozzle 43, the steam generated in the reactor core 41 is guided to a power generation turbine (not shown) or the like to generate power. The main steam pipe 44 is provided with a main steam isolation valve 45, and further provided with a pressure relief valve 46 that operates when an abnormality occurs in the pressure in the reactor pressure vessel 42.

The main steam system valves 45, 46
Requires regular maintenance and inspection. This inspection is performed by removing the lid (not shown) of the reactor pressure vessel 42 and stopping the reactor pressure vessel 4 when the reactor is stopped, such as when refueling.
2 and the reactor well 47 are filled with pure water. Therefore, at the time of inspection, a main steam line plug 48 for closing the main steam nozzle 43 is required to prevent water in the reactor pressure vessel 42 from flowing out of the removed valve seat. This main steam line plug 48 not only seals water, but also performs a main steam isolation valve 45 leak test.
It is necessary to strongly support the main steam line plug 48 so that the main steam line plug 48 does not jump out into the reactor pressure vessel 42 with respect to the pressure of the steam applied to the main steam pipe 44.

FIG. 6 shows an example of the main steam line plug. This main steam line plug 4
8 is formed in a column shape slightly smaller than the inner diameter of the main steam nozzle 43, and along its outer peripheral surface, a hydraulic seal 49 and a pneumatic seal 50, which are freely expandable and contractable, are connected to the main steam nozzle 4.
3 is formed so as to be able to freely contact and separate from the inner peripheral surface. Further, at the end of the main steam line plug 48 on the side of the reactor pressure vessel 42, a hooking plate 51 larger than the shape of the hole at the end of the main steam nozzle 43 is provided. An O-ring 53 is provided between the inner wall 52 of the reactor pressure vessel 42 and the O-ring 53.

As a method of attaching the main steam line plug 48, a main steam line plug attaching device as shown in FIGS. 5, 7 and 8 is used. The main steam line plug mounting device includes a cylinder 5 that pushes a main steam line plug 48 into a main steam nozzle 43 into a back pressure support ring 54 having an outer diameter slightly smaller than the inner diameter of the reactor pressure vessel 42.
The main steam line plug 48 is mounted on the handling beam 56, and is suspended by a ceiling crane 58 via a chain 57 together with the back pressure support ring 54. Pressure vessel 4
2, the main steam line plug 48 is pushed into the main steam nozzle 43 by the cylinder 55, and the hydraulic seal 49 and the pneumatic seal 5 are pressed.
By expanding “0”, it is fixed to the main steam nozzle 43. Then, as shown in FIG. 7 (b), after attaching the main steam line plug 48, the handling beam 56 is pulled up, and the back pressure support ring 54 is raised to the height of the main steam line plug 48, so that the main steam line The plug 48 is supported by the back pressure support ring 54 from the inside.

[0006]

The main steam line plug mounting device is suspended from the operation panel 60 of the refueling floor 59 on the upper part of the reactor pressure vessel 42 by visual inspection. The furnace side mounting bracket (not shown) provided in the main steam line plug mounting device is arranged along the guide groove 61 protruding from the main steam line plug mounting device. For this reason, this operation requires the skill of the operator, and if the hanging position is shifted, the main steam line plug mounting device may stick to the in-furnace bracket. Further, since the back pressure support ring 54 is very large and heavy, equipment such as an overhead crane must be a large-scale facility, and the inside of the furnace becomes narrow and becomes an obstacle. There were problems such as interfering with work. Therefore, when the operation in the furnace is hindered, it is necessary to remove the back pressure support ring 54 each time.
Due to the large size of 4, the removal operation was as difficult as the hanging operation of the main steam line plug mounting device, and it took a lot of time and effort.

Accordingly, the present invention has been devised in order to effectively solve these problems, and an object of the present invention is to improve the main steam nozzle without using a back pressure support ring which deteriorates workability. It is an object of the present invention to provide a new main steam line plug which can be sealed to a main steam line plug.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a plug body inserted into a main steam nozzle of a reactor pressure vessel to seal the same, and a bent portion of the plug body is provided. And a movable piece having an L-shaped cross section, one end of which is rotatably supported on the periphery of the plug body, and which is reciprocally movable at the axis of the plug body. And a pressing member for pressing the movable piece so as to protrude. That is, when the plug main body is inserted into the main steam nozzle, one of the movable pieces pivotally supported on the peripheral portion thereof protrudes outward from the plug main body by the pressing member pressed by the pressure in the main steam pipe, and the main steam nozzle The plug body is caught on the inner wall and is fixed in the main steam nozzle.

[0009] With this, the main steam line plug can be firmly fixed in the main steam nozzle by the pressure in the main steam pipe at the time of the leak test. Therefore, the back pressure support ring causing the above-mentioned inconvenience is provided. There is no need to save labor and simplify the equipment,
It is possible to reduce the occurrence of damage to the reactor-side bracket on the inner wall of the reactor pressure vessel.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side sectional view showing an embodiment of a main steam line plug according to the present invention, FIG. 2 is a side sectional view showing an attached state of a main steam line plug, and FIG. 3 is a main part of FIG. FIG. 4 is a partial cross-sectional perspective view, and FIG.

As shown, the main steam line plug 1 has an outer cylinder 3 which is a plug body having an outer diameter slightly smaller than the inner diameter of the main steam nozzle 2. At the end of the outer cylinder 3 on the side of the reactor pressure vessel 4, a circular latch plate 5 larger than the opening at the end of the main steam nozzle 2 is formed. An O-ring 6 is provided inside the hook plate 5. On the outer peripheral surface of the outer cylinder 3 on the main steam pipe 7 side from the O-ring 6, a groove 8 is formed along the circumferential direction,
A ring-shaped sealing material 9 is fitted and provided in the groove 8. Further, a groove 10 is similarly formed in the vicinity of the end of the outer cylinder 3 on the side of the main steam pipe 7 along the circumferential direction, and a ring-shaped sealing material 11 is fitted and provided in the groove 10. .

Movable pieces 12a and 12b having an L-shaped cross section are axially supported by pins 13a and 13b on the peripheral side of the outer cylinder 3 at two places, an upper side and a lower side, between the seal material 9 and the seal material 11. ,
Is provided. One end of each of the movable pieces 12a and 12b is provided along the longitudinal direction of the outer cylinder 3 so that the movable piece 12a and 12b can move out and out of the outer cylinder 3.
Friction surface portions 15a and 15b for fixing the main steam line plug 1 by contacting the wall surface 14 of the inner peripheral portion of the main steam line are formed. The other end is extended toward the center of the outer cylinder 3 in the radial direction, and is pressed by a pressing member described later.
16b are formed. The pressed parts 16a, 16b
Inside the end of the outer cylinder 3 on the side of the main steam pipe 7 on the side of the main steam pipe 7, the pressure (3 to 4 kg) in the main steam pipe 7 at the time of the leak test.
/ Cm ² ) is provided so as to be able to reciprocate along the axis of the outer cylinder 3. This pressure receiving surface 17
Is formed along the inner peripheral wall of the outer cylinder 3, and a packing 18 is provided on the peripheral edge to keep the airtight.
From the back surface of the pressure receiving surface portion 17, the rods 19 a and 19 b move along the longitudinal direction of the main steam line plug 1 along the pressed portion 16.
a, 16b are provided, and pressing portions 20a, 20b are formed at the distal ends thereof. That is, the pressure in the main steam pipe (main steam nozzle 2) 7 causes
7 is moved to the reactor pressure vessel 4 side together with the pressing portions 20a and 20b, and the pressed portions 1 of the movable pieces 12a and 12b are pressed.
6a and 16b are pushed, and the movable pieces 12a and 12b rotate around the pins 13a and 13b. Thereby, the friction surface portions 15a and 15b are configured to protrude outside the outer cylinder 3 and contact the inner wall surface 14 of the main steam nozzle 2 to be fixed by the frictional force. The pressure receiving surface 17, the rods 19a, 19b and the pressing portions 20a, 20
The pressing member is formed by the member 0b.

A spring 21 is provided between the movable pieces 12a and 12b so as to pull the movable pieces 12a and 12b. When the pressure in the main steam pipe 7 decreases, the friction surfaces 15a and 12b are automatically set. 15b is the inner wall surface 14 of the main steam nozzle 2.
, The main steam line plug 1 is configured to be movable.

By the way, a hydraulic cylinder 22 is provided at the axial center inside the outer cylinder 3 along the longitudinal direction thereof. From the hydraulic cylinder 22, the pressing members 20a, 20b
And a cylinder rod 23 extending in the longitudinal direction is provided. The distal end of the cylinder rod 23 extends beyond the space between the pressing members 20a and 20b, and a locking member 24 for pulling the pressing members 20a and 20b is provided at the distal end so as to extend on both sides. Have been. Therefore, when the hydraulic cylinder 22 pulls the cylinder rod 23, the pressed parts 16a, 16b of the movable pieces 12a, 12b are pushed through the pushing parts 20a, 20b, and the main steam line plug 1 is connected to the main steam nozzle 2. It is configured to be fixed. Except during the leak test, the hydraulic cylinder 22 is used for fixing. When a reverse pressure is applied during the leak test, the hydraulic cylinder 22 is fixed together with the hydraulic cylinder 22 by the force received from the pressure receiving surface 17. . That is, the main steam line plug 1 is
2 is mainly fixed, and is configured to utilize a force received from a back pressure in a leakage test.

Next, the operation will be described along with the work of mounting the main steam line plug 1 and the like.

As shown in FIGS. 2 to 4, the lid 25 of the reactor pressure vessel 4 is removed, and the reactor well 26 is filled with pure water. The main steam line plug 1 is placed on a handling beam 29 provided with a cylinder 28 for pushing the main steam line plug 1 onto a pedestal 27. A plurality of cylinders 28 are provided toward the main steam nozzles 2 at a predetermined angle so that the main steam line plugs 1 correspond to the positions of the main steam nozzles 2 connected to the reactor pressure vessel 4 at the same time. Have been.
This handling beam 29 is suspended by a ceiling crane 31 via a chain 30 and lowered into pure water, and the reactor pressure vessel 4
Is lowered until the height of the main steam nozzle 2 and the height of the main steam line plug 1 coincide with each other, and are engaged with a mounting bracket (not shown) provided there. At this time, the descending operation is performed by the operator visually from the operation panel 33 on the fuel exchange floor 32. However, a large back pressure support ring is not required, and the handling beam 29 is smaller than the back pressure support ring. The operation is relatively easy, and the sticking to the mounting bracket can be reduced. Further, since there is no back pressure support ring, the weight can be reduced, and the size of the overhead crane and the like can be reduced.

Next, the cylinder rod 3 in the cylinder 28
5 and the main steam line plug 1 is connected to the main steam nozzle 2
Push in. At this time, due to the tensile force of the spring 21,
The friction surfaces 15a and 15b of the movable pieces 12a and 12b do not protrude from the outer cylinder 3, and only the frictional force generated between the seal members 9, 11 and the inner wall of the main steam nozzle 2 acts. 1 can be smoothly inserted into the main steam nozzle 2. And the hydraulic cylinder 22
Is driven to cause the movable pieces 12a and 12b to protrude from the outer cylinder 3 and self-hold, and then the handling beam 29 is pulled up.

Next, a leak test of the main steam nozzle 2 is performed while refueling. Pressure is applied to the main steam pipe 7 to make the internal pressure about 3 to 4 kg / cm ² . Then, the pressure receiving surface portion 17 is pressed by this pressure, and the pressing portions 20a,
20b together with the pressure of the hydraulic cylinder 22 and the movable piece 1
The pressed portions 16a and 16b of the 2a and 12b are pushed, and the movable pieces 12a and 12b rotate around the pins 13a and 13b. As a result, the friction surface portions 15a and 15b respectively protrude outside the outer cylinder 3, and the wall surface 1 inside the main steam nozzle 2 is formed.
4 and is firmly fixed by the frictional force generated by contact with the main steam line plug 1 itself.
Can be prevented from jumping out. Therefore, the conventionally used back pressure support ring becomes unnecessary, and a large space can be provided in the furnace during the furnace operation such as fuel exchange. Further, it is not necessary to perform a difficult operation of raising the back pressure support ring, and it is possible to reduce the sticking of the inner wall 34 of the reactor pressure vessel 4 to the mounting bracket.

When such a state is reached, a conventional leak test is performed.
When the internal pressure is reduced and the cylinder rod 23 of the hydraulic cylinder 22 is extended, the pressed parts 16a and 16b are not pressed, and the force of the spring 21 causes the friction surface part 1 to be pressed.
5 a and 15 b are automatically separated from the wall surface 14. Thereafter, the handling beam 29 is lowered again to the level of the main steam line plug 1, and the main steam line plug 1 is pulled out by the cylinder 28. Also at this time, only the frictional force generated between the sealing members 9 and 11 and the inner wall of the main steam nozzle 2 acts, so that the main steam line plug 1 is smoothly pulled out as in the case of insertion.

[0021]

In summary, according to the present invention, in addition to the hydraulic cylinder, the movable piece is pressed and protruded and fixed by the pressure in the main steam nozzle by the pressure in the main steam nozzle. The steam line plug itself can be firmly fixed, eliminating the need for a back pressure support ring as in the prior art. Therefore, it is possible to save labor and to simplify and reduce the size of the apparatus, and it is possible to reduce the sticking of the inner wall of the reactor pressure vessel to the mounting bracket. Also, by reducing the number of parts,
It has an excellent effect that the production cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of a main steam line plug according to the present invention.

FIG. 2 is a side sectional view showing a state in which a main steam line plug is attached.

FIG. 3 is a partial cross-sectional perspective view of a main part of FIG. 2;

FIG. 4 is a sectional view of a main part of FIG. 2;

FIG. 5 is a side sectional view showing a state of attachment of a conventional main steam line plug.

FIG. 6 is a side sectional view showing a conventional main steam line plug.

FIG. 7 is a plan sectional view showing a state of attachment of a conventional main steam line plug.

FIG. 8 is a partial cross-sectional perspective view of a main part of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main steam line plug 2 Main steam nozzle 3 Outer cylinder (plug main body) 4 Reactor pressure vessel 12a, 12b Movable piece 14 Peripheral part 17 Pressure receiving surface part (pressing member) 19a, 19b Rod (pressing member) 20a, 20b Pressing part ( Pressing member)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukihiro Nozawa 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Ishikawashima Harima Heavy Industries, Ltd. Yokohama Engineering Center

Claims (1)

[Claims] 1. A plug body inserted into a main steam nozzle of a reactor pressure vessel for sealing the same, and a bent portion thereof is pivotally supported by a peripheral portion of the plug body, and one end of the plug body is provided at one end of the plug body. A movable piece having an L-shaped cross section which can be retracted outwardly, and a reciprocally movable member provided at an axis of the plug main body, for pressing the movable piece so as to protrude by pressure in the main steam nozzle. A main steam line plug comprising a pressing member.